Can you have multiple columns as primary key?

Can I have 2 columns as primary key?

Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).

How do I set multiple columns as primary key?

We can set PRIMARY KEY constraint on multiple columns of an existing table by using ADD keyword along with ALTER TABLE statement.

How many columns can a primary key have?

In both these examples, primary key contains only one column. In the case of Books table, it is the BookId column and in the case of Authors , it is AuthorId .

How do I make multiple columns a primary key in SQL?

In Table Designer, click the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold down the CTRL key while you click the row selectors for the other columns. Right-click the row selector for the column and select Set Primary Key.